chore(deps): update actions/cache action to v6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
         cache-dependency-path: "**/go.sum"
 
     - name: Cache Go modules
-      uses: actions/cache@v5
+      uses: actions/cache@v6
       with:
         path: |
           ~/.cache/go-build

.github/workflows/publish.yml

@@ -36,7 +36,7 @@ jobs:
         cache-dependency-path: "**/go.sum"
 
     - name: Cache Go modules
-      uses: actions/cache@v5
+      uses: actions/cache@v6
       with:
         path: |
           ~/.cache/go-build
@@ -59,7 +59,7 @@ jobs:
           network=host
 
     - name: Cache Docker outputs
-      uses: actions/cache@v5
+      uses: actions/cache@v6
       with:
         path: /tmp/.buildx-cache
         key: ${{ runner.os }}-buildx-${{ github.sha }}